How do I find out what all symbols are exported from a shared object? - linux

Question

I have a shared object (dll). How do I find out what all symbols are exported from that?

Answer 1

Do you have a "shared object" (usually a shared library on AIX), a UNIX shared library, or a Windows DLL? These are all different things, and your question conflates them all :-(
For an AIX shared object, use dump -Tv /path/to/foo.o.
For an ELF shared library, use readelf -Ws --dyn-syms /path/to/libfoo.so, or (if you have GNU nm) nm -D /path/to/libfoo.so.
For a non-ELF UNIX shared library, please state which UNIX you are interested in.
For a Windows DLL, use dumpbin /EXPORTS foo.dll.

Answer 2

objdump is another good one on linux.

Answer 3

If it is a Windows DLL file and your OS is Linux then use winedump:
$ winedump -j export pcre.dll
Contents of pcre.dll: 229888 bytes
Exports table:
Name: pcre.dll
Characteristics: 00000000
TimeDateStamp: 53BBA519 Tue Jul 8 10:00:25 2014
Version: 0.00
Ordinal base: 1
# of functions: 31
# of Names: 31
Addresses of functions: 000375C8
Addresses of name ordinals: 000376C0
Addresses of names: 00037644
Entry Pt Ordn Name
0001FDA0 1 pcre_assign_jit_stack
000380B8 2 pcre_callout
00009030 3 pcre_compile
...

Answer 4

On *nix check nm. On windows use the program Dependency Walker

Answer 5

see man nm
GNU nm lists the symbols from object files objfile.... If no object
files are listed as arguments, nm assumes the file a.out.

Answer 6

Use: nm --demangle <libname>.so

Answer 7

The cross-platform way (not only cross-platform itself, but also working, at the very least, with both *.so and *.dll) is using reverse-engineering framework radare2. E.g.:
$ rabin2 -s glew32.dll | head -n 5
[Symbols]
vaddr=0x62afda8d paddr=0x0005ba8d ord=000 fwd=NONE sz=0 bind=GLOBAL type=FUNC name=glew32.dll___GLEW_3DFX_multisample
vaddr=0x62afda8e paddr=0x0005ba8e ord=001 fwd=NONE sz=0 bind=GLOBAL type=FUNC name=glew32.dll___GLEW_3DFX_tbuffer
vaddr=0x62afda8f paddr=0x0005ba8f ord=002 fwd=NONE sz=0 bind=GLOBAL type=FUNC name=glew32.dll___GLEW_3DFX_texture_compression_FXT1
vaddr=0x62afdab8 paddr=0x0005bab8 ord=003 fwd=NONE sz=0 bind=GLOBAL type=FUNC name=glew32.dll___GLEW_AMD_blend_minmax_factor
As a bonus, rabin2 recognizes C++ name mangling, for example (and also with .so file):
$ rabin2 -s /usr/lib/libabw-0.1.so.1.0.1 | head -n 5
[Symbols]
vaddr=0x00027590 paddr=0x00027590 ord=124 fwd=NONE sz=430 bind=GLOBAL type=FUNC name=libabw::AbiDocument::isFileFormatSupported
vaddr=0x0000a730 paddr=0x0000a730 ord=125 fwd=NONE sz=58 bind=UNKNOWN type=FUNC name=boost::exception::~exception
vaddr=0x00232680 paddr=0x00032680 ord=126 fwd=NONE sz=16 bind=UNKNOWN type=OBJECT name=typeinfoforboost::exception_detail::clone_base
vaddr=0x00027740 paddr=0x00027740 ord=127 fwd=NONE sz=235 bind=GLOBAL type=FUNC name=libabw::AbiDocument::parse
Works with object files too:
$ g++ test.cpp -c -o a.o
$ rabin2 -s a.o | head -n 5
Warning: Cannot initialize program headers
Warning: Cannot initialize dynamic strings
Warning: Cannot initialize dynamic section
[Symbols]
vaddr=0x08000149 paddr=0x00000149 ord=006 fwd=NONE sz=1 bind=LOCAL type=OBJECT name=std::piecewise_construct
vaddr=0x08000149 paddr=0x00000149 ord=007 fwd=NONE sz=1 bind=LOCAL type=OBJECT name=std::__ioinit
vaddr=0x080000eb paddr=0x000000eb ord=017 fwd=NONE sz=73 bind=LOCAL type=FUNC name=__static_initialization_and_destruction_0
vaddr=0x08000134 paddr=0x00000134 ord=018 fwd=NONE sz=21 bind=LOCAL type=FUNC name=_GLOBAL__sub_I__Z4funcP6Animal

Answer 8

You can use gnu objdump. objdump -p your.dll. Then pan to the .edata section contents and you'll find the exported functions under [Ordinal/Name Pointer] Table.

Answer 9

Usually, you would also have a header file that you include in your code to access the symbols.